Evaluation of human epidermal growth factor receptor 2 expression in colorectal cancer and its correlation with clinicopathological variables

Context: Colorectal cancer is the third most common cancer in men and the second most common cancer in women worldwide. Overexpression of human epidermal growth factor receptor 2 (HER2) in breast and gastric cancer is associated with poor prognosis. However, in colorectal cancer, there are no specific guidelines for immunohistochemical interpretation of HER2. Furthermore, there are conflicting reports regarding correlation of clinicopathological parameters with HER2 expression. Aim: The present study was conducted to determine the frequency of HER2 expression in colorectal cancer and its correlation with clinicopathological variables, if any. Methods: Resection specimens for colorectal cancer over a 2-year period were included in this retrospective study. HER2 immunostaining was done using a monoclonal antibody followed by evaluation of pattern and intensity of staining along with correlation of cells with membranous positivity. Clinicopathological parameters such as age, gender, tumor location, histological subtype of tumor along with tumor stage and grade were analyzed using Fisher's exact test for significance. Results: Of the 50 cases analyzed, 70%, 28%, and 2% were conventional, mucinous, and signet cell ring adenocarcinomas, respectively. The majority were moderately differentiated (56%) and most of the cases presented at Stage III. Weak-to-moderate cytoplasmic positivity was seen in 18% cases, while one case each (2%) showed combined cytoplasmic-membranous and complete membranous positivity, respectively. No significant correlation could be established between HER2 immunostaining and histological subtype or tumor stage/grade. Conclusions: Colorectal cancer demonstrates a very low membranous positivity to HER2 immunostaining. HER2 expression in colorectal cancer has no correlation with clinicopathological variables such as tumor grade, stage, and histological subtype. HER2 does not appear to have any prognostic role to play in colorectal cancer in the context of Indian population.